2021-04-07 14:41:27

by Christophe Leroy

Subject: Re: [PATCH v2 7/8] crypto: ccp: Use the stack and common buffer for INIT command

Le 07/04/2021 à 00:49, Sean Christopherson a écrit :
> Drop the dedicated init_cmd_buf and instead use a local variable. Now
> that the low level helper uses an internal buffer for all commands,
> using the stack for the upper layers is safe even when running with
> CONFIG_VMAP_STACK=y.
>
> Signed-off-by: Sean Christopherson <[email protected]>
> ---
> drivers/crypto/ccp/sev-dev.c | 10 ++++++----
> drivers/crypto/ccp/sev-dev.h | 1 -
> 2 files changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index e54774b0d637..9ff28df03030 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c
> @@ -233,6 +233,7 @@ static int sev_do_cmd(int cmd, void *data, int *psp_ret)
> static int __sev_platform_init_locked(int *error)
> {
> struct psp_device *psp = psp_master;
> + struct sev_data_init data;

struct sev_data_init data = {0, 0, 0, 0};

> struct sev_device *sev;
> int rc = 0;
>
> @@ -244,6 +245,7 @@ static int __sev_platform_init_locked(int *error)
> if (sev->state == SEV_STATE_INIT)
> return 0;
>
> + memset(&data, 0, sizeof(data));

Not needed.

> if (sev_es_tmr) {
> u64 tmr_pa;
>
> @@ -253,12 +255,12 @@ static int __sev_platform_init_locked(int *error)
> */
> tmr_pa = __pa(sev_es_tmr);
>
> - sev->init_cmd_buf.flags |= SEV_INIT_FLAGS_SEV_ES;
> - sev->init_cmd_buf.tmr_address = tmr_pa;
> - sev->init_cmd_buf.tmr_len = SEV_ES_TMR_SIZE;
> + data.flags |= SEV_INIT_FLAGS_SEV_ES;
> + data.tmr_address = tmr_pa;
> + data.tmr_len = SEV_ES_TMR_SIZE;
> }
>
> - rc = __sev_do_cmd_locked(SEV_CMD_INIT, &sev->init_cmd_buf, error);
> + rc = __sev_do_cmd_locked(SEV_CMD_INIT, &data, error);
> if (rc)
> return rc;
>
> diff --git a/drivers/crypto/ccp/sev-dev.h b/drivers/crypto/ccp/sev-dev.h
> index 0fd21433f627..666c21eb81ab 100644
> --- a/drivers/crypto/ccp/sev-dev.h
> +++ b/drivers/crypto/ccp/sev-dev.h
> @@ -46,7 +46,6 @@ struct sev_device {
> unsigned int int_rcvd;
> wait_queue_head_t int_queue;
> struct sev_misc_dev *misc;
> - struct sev_data_init init_cmd_buf;
>
> u8 api_major;
> u8 api_minor;
>

2021-04-17 12:43:47

by Paolo Bonzini

Subject: Re: [PATCH v2 7/8] crypto: ccp: Use the stack and common buffer for INIT command

On 07/04/21 07:20, Christophe Leroy wrote:
>>
>> +    struct sev_data_init data;
>
> struct sev_data_init data = {0, 0, 0, 0};

Having to count the number of items is suboptimal. The alternative
could be {} (which however is technically not standard C), {0} (a bit
mysterious, but it works) and memset. I kept the latter to avoid
touching the submitter's patch too much.

Paolo